1. Field of Invention
Aspects and embodiments relate generally to telecommunications and, more particularly, to color ringback tone services.
2. Discussion of Related Art
Ringback tones are the audio sounds heard by a calling party while waiting for a connection to a called party to be completed. The most commonly used ringback tone is the familiar “ring ring” sound heard until the call is answered. One example of a system and method for providing audible ringback tones in a telecommunications network is described in PCT patent publication number WO05122542 entitled “METHOD AND SYSTEM FOR PROVIDING RINGBACK TONES” and having an International filing date of Dec. 22, 2005.
At present, color ringback tone (CRBT) is a technology used predominantly in mobile phone networks, and also in some voice over IP (VoIP) systems. Instead of hearing the familiar “ring ring” tone when calling someone, CRBT allows a subscriber (e.g., a mobile phone user) to play their favorite tune, sound or jingle to incoming callers. With the ability to choose the ring tone a caller will hear, subscribers have an instant way to express their own individuality, and to provide a customized response to the calling party. Optionally, the traditional “ring ring” tone can be mixed with the subscriber's chosen music or sound, so as not to confuse callers unfamiliar with the CRBT service.
An attractive feature of CRBT is that this network-based service is independent of both handsets and Subscriber Identity Modules (SIMs). Therefore, users (subscribers or callers) are not required to have the latest phone or a particular brand of phone, and operators have the flexibility to offer personalized ring back services to all types of subscribers. Such personalization services are usually chargeable services. Thus, CRBT provides operators with the ability to easily generate additional revenue from service management, using a wealth of existing subscriber data.
An example of a system and method for implementing color ringback tones is discussed in PCT patent publication number WO06075809 entitled “METHOD AND APPARATUS FOR PROVIDING SOUNDS FOR SUBSTITUTING RINGBACK TONES” and having an International filing date of Jan. 12, 2005.
Speech synthesis is the artificial production of human speech, and can be accomplished by a computer using hardware, software, or a combination of both. A “text to speech” system converts normal language text into speech. The most important qualities of a speech synthesis system are generally considered by those of ordinary skill in the art to be naturalness and intelligibility. Naturalness describes how closely the output sounds like human speech, while intelligibility is the ease with which the output is understood. The ideal speech synthesizer is both natural and intelligible.
There are two primary technologies for generating synthetic speech waveforms, namely concatenative synthesis and formant synthesis. Concatenative synthesis is based on the concatenation (or stringing together) of segments of recorded speech. Generally, concatenative synthesis produces the most natural-sounding synthesized speech; however, differences between natural variations in speech and the nature of the automated techniques for segmenting the waveforms sometimes result in audible glitches in the output. Formant synthesis does not use human speech samples at runtime. Instead, the synthesized speech output is created using an acoustic model. Parameters such as fundamental frequency, voicing, and noise levels are varied over time to create a waveform of artificial speech. Although many systems based on formant synthesis technology generate artificial, robotic-sounding speech, formant-synthesized speech can be reliably intelligible, even at very high speeds, avoiding the acoustic glitches that commonly plague concatenative systems. Both methods are widely used, and the particular goals and needs of a system may influence selection of the method of speech synthesis for that system.